Coexistence of topological node surface and Dirac fermions in phonon-mediated superconductor YBC.

Phys Chem Chem Phys

School of Physical Science and Technology, Southwest University, Chongqing 400715, China.

Published: January 2024

The interaction between nontrivial topology and superconductivity in condensed matter physics has attracted tremendous research interest as it could give rise to exotic phenomena. Herein, based on first-principles calculations, we investigate the electronic structures, mechanical properties, topological properties, dynamic stability, electron-phonon coupling (EPC), and superconducting properties of the synthesized real material YBC. It is a tetragonal structure with 4/ symmetry and exhibits excellent stability. The calculated electronic band structures reveal that a zero-dimension (0D) Dirac point and two-dimensional (2D) nodal surface coexist near the Fermi level. A spin-orbit coupling (SOC) Dirac point with the topological Fermi arc is observed on the (001) surface. These nodal surfaces are protected by a two-fold screw axis and time-reversal symmetry. Based on the Bardeen-Cooper-Schrieffer theory, the superconducting transition temperature () in the range 1.25-4.45 K with different Coulomb repulsion constant * for YBC is estimated to be consistent with previous experimental results. In addition, the EPC is mainly from the coupling between the d and d orbitals of the Y atom and low-energy phonon modes. The presence of superconductivity and nontrivial topological surface state in YBC suggests that it may be a candidate material for topological superconductors.

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Source
http://dx.doi.org/10.1039/d3cp03678bDOI Listing

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